Biliquid foam entrapment

ABSTRACT

A discrete powder which comprises particles in which a biliquid foam has been entrapped with a matrix of a polymeric material. A process for the preparation of these discrete powders comprises the steps of: i) preparing a biliquid foam, ii) forming a dispersion of the biliquid foam in an aqueous solution, suspension or dispersion of a polymeric material, and iii) subjecting the dispersion to drying under conditions such that a discrete powder is formed.

The present invention relates to biliquid foam entrapment and, inparticular, to a biliquid foam entrapped within a matrix of a polymericmaterial which is in the form of a discrete powder.

The entrapment of oils or oil soluble substances (especially perfumesand coloured dye precursors) in microcapsules and their subsequentcoating onto paper and other surfaces is well known in the art.Microcapsules of this type comprise individual droplets of oil or oilsoluble substances (of size ranging from sub-micrometre to tens ofmillimetres in diameter) around which polymer walls have been formed byone of a number of chemical processes. Usually such microcapsules areprepared as an aqueous suspension which is then capable, with theaddition of suitable modifying reagents, of being sprayed or printedonto paper and other surfaces. The object in so doing is usually toprevent the evaporation of volatile substances (for example, perfumes)or the degradation or chemical reaction of oil soluble species (forexample, colourless dye precursors) until the microcapsules are brokenby the application of shear forces by scratching or scraping the coatedsurface with the consequent release of their contents. Such coatingsfind major uses, for example, in the forms of “scratch and sniff”perfume coatings or NCR (No Carbon Required) paper.

However, these microcapsules suffer from a number of disadvantages.

Firstly, the process by which microcapsules are formed is a lengthy anduncertain one in which control over temperature, pH and the absence ofany form of contamination is essential. The formation of microcapsules,for example, by complex coacervation from gelatin and an anioniccomplexing species such as gum acacia takes many hours and demands veryclose control of pH, temperature and cooling rate. Similarly, theformation of microcapsule walls from aminoplast resins, such asmelamine-formaldehyde or urea-formaldehyde takes at least eight hoursduring which precise control over all controllable parameters needs tobe effected. Moreover, the effectiveness and completeness of anyindividual encapsulation process (and therefore the quality of themicrocapsules so formed) depends largely on the chemical nature of theoil and/or oil soluble substances being encapsulated.

A further disadvantage of microcapsulation is that the thickness andtherefore the strength of the microcapsule wall is variable and is noteasily is controllable and varies with the nature of the oil oroil-soluble substances being encapsulated. Thus microcapsules made bythe same process but from different oils may have widely differingstrengths and resistance to breakage during the printing process andduring subsequent storage and use.

A yet further disadvantage of microencapsulation is the limited numberof chemical processes and the limited number and type of polymeric wallmaterials which are available to form them. The choice as to theproperties of the wall materials is consequently limited with regard totheir flexibility, tensile strength, permeability, chemical inertness,mammalian toxicity and other properties including solubility and meltingpoint (if any). In addition, some of the chemicals commonly used in thewall forming process are themselves highly irritating and may themselvesbe toxic such, for example, as the use or release of formaldehyde (apotential carcinogen) during the manufacture of aminoplast resin walls.Moreover, the remaining traces of formalin in the resulting microcapsulesuspension are virtually impossible to eliminate to below acceptablelevels for uses of microcapsules and requires special precautions to betaken during the manufacturing process.

Whilst many of the processes to produce microcapsules producedispersions of the microcapsules in a fluid medium, they can also beproduced in the form of a powder.

Other methods of encapsulating oil within a powder are generally basedupon the drying of an oil-in-water dispersion. Examples of this priorart include EP-B-0938932 which discloses a process for manufacturing acosmetic and/or dermatological powder in which an oil-in-waterdispersion comprising at least one modified starch is dehydrated to forma powder and U.S. Pat. No. 6,129,906 in which a granular powder isformed by spray drying an aqueous dispersion of a silicone oil and awater-soluble carrier, the silicone oil being present in the dispersionas discrete droplets having a droplet size in the range of from 0.5 μmto 20 μm.

WO 99/05299 discloses a surface coating in which droplets of a non-polarsubstance are trapped within a polymer film, the surface coating beingprepared by drying a dispersion of a film forming polymer containingdroplets of a suspended biliquid foam or emulsion. Surface coatings onlyare disclosed and this reference does not teach the drying of thedispersions to form a powder.

We have now developed a discrete powder which is based upon theencapsulation of a biliquid foam.

Accordingly, in one aspect of the present invention provides a discretepowder which comprises particles in which a biliquid foam has beenentrapped within a matrix of a polymeric material.

In another aspect the present invention provides a process for thepreparation of a discrete powder which comprises a biliquid foamentrapped within a matrix of a polymeric material, which processcomprises the steps of:

-   -   i) preparing a biliquid foam,    -   ii) forming a dispersion of the biliquid foam in an aqueous        solution, suspension or dispersion of a polymeric material, and    -   iii) subjecting the dispersion to drying under conditions such        that a discrete powder is formed.

The discrete powder of the present invention is preferably produced byspray drying of the dispersion.

Biliquid foams are known in the art and are described in the followingliterature references by Sebba: “Biliquid foams”, J. Colloid andInterface Science, 40 (1972) 468-474; and “The Behaviour of Minute OilDroplets Encapsulated in a Water Film”, Colloid Polymer Sciences, 257(1979) 392-396. Neither of these articles suggest that biliquid foamsmight be used in the preparation of spray dried powders.

U.S. Pat. No. 4,486,333 to Sebba describes a particular method for thepreparation of biliquid foams by agitating a hydrogen bonded liquidcontaining a soluble surfactant to produce a gas foam and intermittentlyadding to the gas foam a non-polar liquid which is immiscible with thehydrogen bonded liquid, the surfactant-containing hydrogen bonded liquidbeing selected to provide a spreading coefficient equal to or greaterthan zero.

The oil-based biliquid foam used in the spray dried powders of thepresent invention well preferably comprise from 70 to 95% by weight ofthe oil phase and from 5 to 30% by weight of the continuous phase. Asurfactant to stabilise the biliquid foam may also be included in anamount of from 0.01 to 3%, preferably from 0.1 to 1% based on the totalweight of rhe biliquid foam. The surfactant may dissolve in either theoil phase, the continuous phase or both phases of the biliquid foam.Generally, the level of surfactant used in the formation of the biliquidfoams is lower than the level used in the preparation of conventionaldry emulsion systems.

Oils which may be used in the biliquid foam will in general besubstantially water immiscible and liquid at room temperature and maybe, for example, a cyclomethicone, dimethicone, phenyl trimethicone,dimethiconol, dimethicone copolyol, trimethylsiloxy-silicate, anemollient ester such as isopropyl isostearate, lanolate, myristate orpalmitate, or octyl palmitate, a glyceride such as avocado oil, coconutoil, soybean oil or sunflower oil, or a caprylic/capric triglyceride, alanolin oil, orange oil, mineral oil or natural oil, or oleyl alcohol,or any other oil generally known for this purpose, or mixtures of theforegoing. It will be understood that the present invention enables oilsto be incorporated into the powder which would normally be difficult toincorporate into conventional dry emulsion systems.

It will be understood that the oil phase of the biliquid foam maycontain or consist of one or more active ingredients such as fragrances,flavours, deodorisers, perfumes, pharmaceuticals, sunscreens, dyes,pesticides, insect repellants, herbicides, etc.

The biliquid foam may contain, as described above, a low level of asurfactant which may be, for example:

-   -   a cationic surfactant such as an amidoamine, a quaternary        ammonium compound or a sulphonium salt;    -   an amphoteric surfactant such as an acylamino-acid, an        N-substituted alkylamine, an N-alkyl-β-amino-propionate, an        N-alkylbetaine, an alkylimidazoline or a sulphobetaine;    -   an anionic surfactant such as an acyl-lactate,        N-acylsarcosinate, alkyl-carboxylate (either mono- or        polyvalent), alkyl ether carboxylate, N-alkyl-glutamate, fatty        acid-peptide condensate, phosphated ethoxylated alcohol, alkyl        sulphate, ethoxylated alkyl sulphate, alpha-olefin sulphonate or        ester-linked sulphonate;    -   a nonionic surfactant such as an alkanolamide, 5 amine oxide,        ester of a polyhydric (for example an ester of an ethylene,        diethylene or propylene glycol, or glycerol or a polyglycerol,        or sorbitan, glucose or sucrose), a polyoxyethylene or        polyoxypropylene derivative of an alcohol, amide or ester, or a        polyoxyethylene/polyoxypropylene block copolymer;    -   or a suitable compatible mixture of these surfactants.

The continuous phase of the biliquid foam is generally an aqueous phasewhich may include therein a is substantial level of a C₁-C₄ (watermiscible) alcohol, or ethylene glycol or mixtures thereof.

The continuous phase of the biliquid foam may include thereinpreservatives, stabilizers or other materials known in the art.

Methods of producing biliquid foams are described in U.S. Pat. No.4,486,333 involving the preliminary formation of a gas foam in order toprovide a sufficiently large surface area on which the biliquid foam cansubsequently be formed. It has been found that the prior formation of agas foam is not required to manufacture a stable biliquid foam, providedthat a suitable stirring mechanism is provided in the manufacturingvessel. An aspect of the present invention is the ability to manufacturebiliquid foams without the preliminary formation of gas foam, by the useof a tank incorporating a suitable stirring mechanism.

Such an apparatus comprises a tank provided with a stirrer in which thestirrer blade breaks the interface between the liquid and air. Adelivery device is provided through which the oil phase (waterimmiscible liquid), which will comprise the internal phase of thedispersion, is delivered to the tank. The design of the delivery deviceis such that the rate of addition of the internal phase fluid can becontrolled and varied during the production process. A feature of theproduction process is that the internal (oil) phase is added to thestirred aqueous phase slowly at first until sufficient droplets havebeen formed to constitute a large, additional surface area for the morerapid formation of new droplets. At this point, the rate of addition ofthe oil phase may be increased.

The production process consists of the following steps:

-   -   1. The addition of one or more chosen surfactants to one or        other or both phases (as previously determined by experiment)    -   2. The charging of the aqueous phase into the bottom of a        process vessel.    -   3. The incorporation of the stirrer into the vessel so that it        stirs the surface of the aqueous phase.    -   4. Adjustment of the stirrer speed to a previously determined        level.    -   5. The slow addition of the internal phase whilst continuing to        stir at the prescribed speed.    -   6. The speeding up of the rate of addition of the oil phase once        a prescribed amount (usually between 5% and 10% of the total        amount to be added) has been added.

The stirring rate and the rate of addition of the oil phase arevariables, the values of which depend upon the detailed design of themanufacturing plant (in particular, the ratio of tank diameter toimpeller diameter), the physico-chemical properties of the oil phase andthe nature and concentrations of the chosen surfactants. These can allbe pre-determined by laboratory or pilot plant experiment.

It will be understood by those skilled in the art that othermanufacturing methods may be used to produce the biliquid foams, asappropriate.

In the present invention the biliquid foam is entrapped within apolymeric material and thereby forms a discrete powder.Water-dispersible or water-soluble film forming polymers of many typesare well known and include cellulose derivatives (for example,carboxymethylcellulose, hydroxyethylcellulose, cetylhydroxycellulose,hydroxypropylcellulose, hydroxypropylmethylcellulose,hydroxyethylmethylcellulose and methylcellulose), gelatin, gum arabic,gum acacia, gellan gum, shellac, carragenan, natural starches, modifiedstarches, xanthan gums, alginates, dextrins, polyvinyl alcohol,polyvinyl acetate, polyvinyl pyrollidone or polyamides and other waterdispersible or water soluble film forming agents known in the art. Thepresent invention may include the use of all the above singly or incombination. Certain of the polymers may only be water-dispersible orwater-soluble at elevated temperatures and therefore in the preparationof the dispersions of the biliquid foams and during spray drying, thedispersion mixture would be used at these elevated temperatures.Industrial, food or pharmaceutical grade polymers may be used, dependingupon the end use of the dried powder.

In carrying out the process of the present invention for forming adiscrete powder the suspension of the biliquid foam in an aqueoussolution, suspension or dispersion of the polymeric film former is driedunder conditions such that a discrete powder is formed. Preferably thesaid dispersion is spray dried. The choice of suitable spray dryingconditions will be within the knowledge of a person skilled in the artand will depend upon various factors, including the melt temperature ofthe polymeric material, the amount of water contained in the dispersion,the ratio of polymeric material to the biliquid foam etc. Generally theinlet temperature for the spray dryer will be in the range of from 170°to 210° C. and the outlet temperature will be in the range of from 85 to110° C.

The dispersion which is subjected to drying may also incorporate astructuring or gelling agent therein. Any such agent must, however,shear thin when the dispersion is subjected to atomisation forces, forexample during spray drying. Such a structuring or gelling agent mayassist in maintaining the integrity of the dispersion prior to thedrying process.

Typically, in carrying out the present invention the biliquid foam willhave a mean droplet size in the range of from 1 to 45 micrometres Abiliquid foam having such a droplet size can generally be produced underlow shear conditions. For the purpose of the present invention thedroplet size of the majority of the droplets of the biliquid foam shouldpreferably be further reduced to below 12 micrometres, for example byusing higher shear conditions.

The biliquid foam is then mixed with an aqueous solution, suspension ordispersion of the polymeric material under conditions which generate ahomogeneous dispersion. For example,.using gentle stirring or using ahigh shear device, such as a Roto Stator mixer.

It will be understood that although spray drying is the preferred methodof producing the discrete powders of the present invention, other dryingtechniques, such as freeze drying and fluidized bed granulation can alsobe used.

The discrete powders of the present invention generally incorporate highlevels of oil entrapped within the polymeric material, typically from 5to 50% by weight, preferably from 20 to 40% by weight based on theweight of the powder.

The discrete powders of the present invention will generally have a meanparticle size in the range of from 5 to 150 μm. It will be understood,however, that larger particle sizes may be obtained by the use oftechniques known in the art, such as granulation. The size range maythen be of the order of 5 μm to 1 mm.

The invention provides a means of controlling the rate of release of theoil entrapped within the polymeric material by exercising control overthe concentration and ratio to the biliquid foam of the film formingpolymer in solution or suspension and thereby controlling the thicknessand strength of the film forming the outside of the particles.

The invention also allows for release of the oil by dissolution of thefilm by contact with water or other polar solvent. For example, thepowder may contain a fragrance or aromatherapy oil and be sprinkled ontowater in a bath. In addition, the water-soluble or water dispersiblefilm forming polymer may be partially or wholly crosslinked to render itpartially or totally water insoluble by which means the rate of releaseof the entrapped biliquid foam may be controlled by the speed or absenceof dissolution when the powder makes contact with water or other polarliquid in which it might otherwise be soluble. Different powders couldthen be mixed together in order to give a range of release rates, ifrequired.

Alternatively, the choice of film-forming polymer may be such that it issensitive to acidity or alkalinity so that the release of the entrappedoil may be determined by a change of pH or by the presence of anotherchemical species with which the film-forming polymers may react, sorendering it permeable or unstable. Alternatively, the choice offilm-forming polymer may be such that it is sensitive to temperature orbiological conditions. The powder may alternatively comprise a polymerwhich melts at a known and predetermined temperature to release theentrapped oil.

In one embodiment, the entrapped biliquid foam may comprise a perfumewhich, when dried into a discrete powder will behave and performprecisely as a conventional, microencapsulated “scratch and sniff”perfume as previously described. Furthermore, an encapsulating polymermay be chosen that allows the release of the perfume by diffusion overtime, such as in a room fragrancing device.

In another embodiment, a perfume or deodorising composition is entrappedaccording to this invention in a discrete powder which is incorporatedinto a diaper, incontinence pad or feminine hygiene product duringmanufacture so that the perfume or deodorising composition is releasedon contact with aqueous bodily fluids when the diaper, incontinence pador feminine hygiene product is used, thereby masking or neutralising anydisagreeable odour.

In another embodiment, the powder may be provided as a dry skin washcomposition containing a cleansing, moisturising or emollient oil. Inthis instance, the dry powder would be applied to the skin and rubbedeither with or without the addition of water in order to release theentrapped from the polymer matrix.

In another embodiment, the biliquid foam comprising a household cleaningoil, such as orange oil may be entrapped in water soluble polymer powderparticles on a suitable applicator together with other reagents (forexample, an abrasive material, such as a pumice or water solubleantimicrobial agents) to form a dry surface which, when wetted, becomesan effective hard surface cleaning product.

In another embodiment the powder may be provided as a carpet or fabriccleaning or deodorizing composition and the oil will then comprise asuitable cleaning or deodorizing oil.

In yet another embodiment, the matrix forming polymer may comprise abrittle film which ruptures easily when deformed so releasing theentrapped non-polar substance. In one application of this embodiment,the powder may be coated onto a flexible film which may, for example, beshrunk onto the cap of a consumer product such that if the flexible filmis removed, the particles rupture so releasing the non-polar substancewhich, in this instance, may be the colourless precursor of a coloureddye which, on release, undergoes a chemical change to become highlycoloured. This embodiment thereby gives a clear indication as to whetheror not a closure has been tampered with. Alternatively, the powder maybe incorporated into the film forming polymer precursor during thepreparation of the flexible films. The film forming polymer precursorwill be chosen from suitable materials which do not dissolve the powder.

In a still further embodiment of the present invention the discretepowder particles may be granulated or formed into tablets according totechniques known in the art. In these processes the powder may becombined with one or more binders, excipients, fillers, disintegrants orother suitable materials.

The powders of the present invention may also be incorporated duringextrusion of a polymer melt. In this instance the polymer system will beselected such that the polymer melt does not dissolve the polymer usedin the preparation of the powders of the invention. The melt temperatureof the polymer used in forming the powders will also need to be greaterthan that of the extruding polymer.

The oil which is incorporated into the powder may be chosen such that itboils at a given temperature, thereby rupturing the powder, or film orextruded polymer containing the powder, thereby causing a triggerrelease of the oil. This embodiment may be used, for example, for therelease of a latent catalyst which may enable controlled chemicalmodification of the extruding polymer to take place.

A still further release mechanism may be the use of polymeric systems inthe formation of the powders of the invention which are biodegradable,thermally degradable or photodegradable. The oil contained in thepowders would then be released on degradation of the polymers.

The present invention will be further described with reference to thefollowing Examples.

Preparation of Biliquid Foams

Preparation 1

A biliquid foam was prepared from the following ingredients. IngredientsWeight (g) % Aqueous Phase Water 396 9.9 Sodium lauryl ether 4 0.1sulphate Oil Phase Volpo L3 36.4 0.9 Medium viscosity white 3563.6 89.1mineral oil Total 4000 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase and stirring with a flat bladed stirrer at 300 rpm until the meandroplet size was 15-20 micrometres.

A 1 kg sample was removed and this was stirred with a flat bladedstirrer at 500 rpm until the mean droplet size was 11 micrometres.

Preparation 2

Ingredients Weight (g) % Aqueous Phase Water 148.5 9.9 Tween 20 1.5 0.1Oil Phase PEG25 castor oil 13.5 0.9 KMC 1269.7 84.65 Pergascript RedI-6B 66.8 4.45 Total 1500.0 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase and stirring with a flat bladed stirrer at 116 rpm. The meandroplet diameter was 35 micrometres. The stirrer speed was thenincreased to 250 rpm and stirred until the mean droplet size was lessthan 12 micrometres.

Preparation 3

Ingredients Weight (g) % Aqueous Phase Water 47.67 9 Sodium lauryl ether0.53 0.1 sulphate Oil Phase Laureth 3 4.77 0.9 Dow Corning 200 50cst476.74 90.0 Total 529.71 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase whilst stirring with a flat bladed stirrer at 200 rpm for 45minutes.

Preparation 4

Ingredients Weight (g) % Aqueous Phase Water 44.97 9 Sodium lauryl ether0.5 0.1 sulphate Kathon 1CG II 0.03 0.006 Oil Phase Oleth 10 4.5 0.9Orange oil 450.0 90.0 Total 500 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase whilst stirring with a flat bladed stirrer at 200 rpm for 45minutes.

Preparation 5

Ingredients Weight (g) % Aqueous Phase Water 52.60 9.8 Sodium laurylether 0.532 0.1 sulphate Kathon 1CG II 0.026 0.0048 Oil Phase Etocas 254.78 0.9 (PEG25 Castor oil) Rose oil fragrance 478.44 89.2 L301844 Total536.378 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase whilst stirring with a flat bladed stirrer at 200 rpm for 45minutes.

Preparation 6

Ingredients Weight (g) % Aqueous Phase Water 14.85 9.9 Tween 20 0.15 0.1Oil Phase Oleth 10 1.35 0.9 Octyl methoxy cinnamate 133.65 89.1 Total150 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase whilst stirring with a flat bladed stirrer at 200 rpm for 45minutes.

Preparation 7

Ingredients Weight (g) % Aqueous Phase Water 11.29 8.79 Tween 20 0.260.20 Oil Phase PEG25 castor oil 0.64 0.5 Oleth 10 0.64 0.5 HouseholdFragrance oil 115.55 90 Total 128.38 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase whilst stirring with a flat bladed stirrer at 200 rpm for 45minutes.

Preparation 8

Ingredients Weight (g) % Aqueous Phase Water 9 9 Laureth 23 1 1 OilPhase Gransil GCM-5 49.24 49.24 Cetearyl isonanoate 7.78 7.78 Isopar K7.78 7.78 Dow Corning 200 50cst 0.97 0.97 Gransil DMCM-5 24.25 24.25Total 100 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase and stirring with a flat bladed stirrer at 174 rpm. The stirrerspeed was increased to 300 rpm to help with the inclusion of the oilbefore continuing to stir at 174 rpm until the mean droplet size was 11μm.

Preparation 9

Ingredients Weight (g) % Aqueous Phase Water 9.9 9.9 Tween 20 0.1 0.1Oil Phase Ibuprofen 4.5 4.5 Isopropyl myristate 84.5 84.5 Laureth 3 1 1Total 100 100

The biliquid foam was prepared by adding the oil phase (ibuprofen fullydissolved in the isopropyl myristate) to the aqueous phase and stirringwith a flat bladed stirrer at 174 rpm. The preparation was stirred afterthe inclusion of the oil until the mean droplet size was 18 micrometres.

Preparation 10

Ingredients Weight (g) % Aqueous phase Water 49.5 9.9 Tween 20 0.5 0.1Oil Phase PEG25 castor oil 2.5 0.5 Oleth 10 2.5 0.5 Household Fragranceoil 445 89 Total 500 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase whilst stirring with a flat bladed stirrer at 220 rpm for 60minutes. The procedure was repeated twice more to generate three 500 gbatches which were blended together for use in spray drying examples.

Preparation 11

Ingredients Weight (g) % Aqueous Phase Water 99 9.9 Sodium lauryl ether1 0.1 sulphate Oil Phase Laureth 4 9 0.9 Mineral oil with red dye 89189.1 Total 1000 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase whilst stirring with a flat bladed stirrer at 110 rpm for 30minutes. The preparation was then sheared at 230 rpm until the dropletsize was less than 10 microns.

Preparation 12

Ingredients Weight (g) % Aqueous Phase Water 39.6 9.9 Tween 20 0.4 0.1Oil Phase Emulsifier A 4 1 Deodorising oil 356 89 Total 500 100

The biliquid foam was prepared by adding the oil phase to the aqueousphase whilst stirring with a flat bladed stirrer at 180 rpm for 60minutes. The preparation was stirred at 230 rpm until the droplet sizewas less than 10 microns.

Emulsifier A Consists of: Ethoxylated isotridecanol (9EO) 52.52%Dipropylene glycol 25.25% PEG 40 Hydrogenated castor oil 22.23%

Preparation of Dispersions and Spray Drying EXAMPLE 1

The dispersion was prepared by stirring the biliquid foam into theaqueous polymer immediately before spray drying. Ingredients Weight (g)% Preparation 1 76.9 7.7 Gum acacia (30% by weight in 923.1 92.3demineralized water) Total 1000 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles34.6% Oil:polymer (dry basis) 20:80 Inlet/outlet temperature 200° C./95°C. Yield 85.2% Comment Product Characterisation Nature of dry particleFine powder Oil encapsulation Good Oil release Moderate amount of looseoil visible on release. Mean droplet size before 1.99 μm spraying

EXAMPLE 2

The dispersion was prepared by stirring the biliquid foam into theaqueous polymer immediately before spray drying. Ingredients Weight (g)% Preparation 1 73.85 8.7 PVP K30 (30% by weight 465.9 54.8 indemineralized water) Mowiol (5% by weight 310.6 36.5 in demineralizedwater) Total 850.4 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles26% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 210° C./110°C. Yield about 100% Comment Product Characterisation Nature of dryparticle Good Oil encapsulation Good Oil release Little visible oil.Mean droplet size before 6.1 μm, peak at 11 μm. spraying

EXAMPLE 3

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymer immediately before spray drying. Ingredients Weight(g) % Preparation 1 100 11.7 Water 74.64 8.7 Maltodextrin (40% by 52.56.1 weight in demineralized water) PVP k30 (30% by weight 630 73.5 indemineralized water) Total 847.14 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 185° C./85°C. increased to 90° c. Yield 17.2% Comment Product slightly dampinitially but spray dried well with higher outlet temperature. ProductCharacterisation Mature of dry particle Good Oil encapsulation Good Oilrelease Slight amount of loose oil visible. Mean droplet size before 1.2μm, peak at 9 μm. spraying

EXAMPLE 4

The dispersion was prepared by stirring the biliquid foam and make upwater into the aqueous polymer immediately before spray drying.Ingredients Weight (g) % Preparation 2 116.67 11.67 Water 66.67 6.67 PVPK30 (30% by weight 816.67 81.67 in demineralized water) Total 1000 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 203° C./95°C. Yield 64.21% Comment -Product Characterisation Nature of dry particleGood Oil encapsulation Good Oil release Little visible free oil. Meandroplet size before 0.58 μm, peaks at 0.15, 0.7 and spraying 12 μm.

EXAMPLE 5

The dispersion was prepared by stirring the biliquid roam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 3 89.9 11.7 Water 67.1 8.7 Maltodextrin (40% by 47.26.1 weight in demineralized water) PVP k30 (30% by weight 566.6 73.5 indemineralized water) Total 770.9 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 195° C./95°C. Yield 56.6% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release No visible oilon surface Mean droplet size before 9.9 μm spraying

EXAMPLE 6

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 4 105.4 13.7 Water 48.8 6.3 Maltodextrin (40% by 614.779.9 weight in demineralized water) Total 768.9 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles45% Oil:polymer (dry basis) 27.8:72.2 Inlet/outlet temperature 195°C./95° C. Yield about 100% Comment Spray dried well ProductCharacterisation Nature of dry particle Good Oil encapsulation Good Oilrelease Little visible oil. Mean droplet size before 1.4 μm spraying

EXAMPLE 7

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 4 101.7 11.7 Water 147.1 16.9 Maltodextrin (40% by266.9 30.6 weight in demineralized water) Gum acacia 355.9 40.8 Total871.6 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 195° C./95°C. Yield 78.3% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release Little visibleoil at surface. Mean droplet size before 1.3 μm spraying

EXAMPLE 8

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 5 81.4 11.7 Water 89.3 12.8 Maltodextrin (40% by 128.318.4 weight in demineralized water) PVP k30 (30% by weight 399.1 57.2 indemineralized water) Total 698.1 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying cower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 195° C./95°C. Yield 66.1% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release No visible oilat surface Mean droplet size before 0.95 μm, peaks at 1 μm and 6.5 μmspraying

EXAMPLE 9

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymer immediately before spray drying. Ingredients Weight(g) % Preparation 6 100 11.7 Water 74.64 8.7 Maltodextrin (40% by 52.56.1 weight in demineralized water) PVP k30 (30% by weight 630 73.5 indemineralized water) Total 857.14 100

Spray drying conditions Pilot plane Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 175° C./95°C. Yield 92% Comment Spray dried well Product Characterisation Nature ofdry particle Good Oil encapsulation Good Oil release Minimal free oilvisible on surface. Mean droplet size before 0.7 μm, peak at 10 μmspraying

EXAMPLE 10

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 7 89.9 11.7 Water 67.1 8.7 Maltodextrin (40% by 47.26.1 weight in demineralized water) PVP k30 (30% by weight 566.6 73.5 indemineralized water) Total 770.9 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 195° C./90°C. Yield 93.8% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release Little visibleoil on surface. Mean droplet size before 2.39 μm, peaks at 1.5 μm andspraying 7.5 μm

EXAMPLE 11

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 8 67.2 11.3 Water 50.2 8.5 Maltodextrin (40% by 53.39.0 weight in demineralized water) PVP k30 (30% by weight 423.3 71.3 indemineralized water) Total 594 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisacion was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 29:71 Inlet/outlet temperature 195° C./95°C. Yield 82.3% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release No visible freeoil Mean droplet size before 7.26 μm, peak at 11 μm spraying

EXAMPLE 12

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 9 79.1 11.7 Water 59.1 8.7 Maltodextrin (40% by 41.56.1 weight in demineralized water) PVP k30 (30% by weight 498.5 73.5 indemineralized water) Total 678.1 100

Spray drying conditions Pilot plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 195° C./98°C. Yield 76.5% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release Minimal free oilvisible on surface. Mean droplet size before 18.71 μm spraying

Compression of the powder was performed using a tabletting machine.Successful tablets were produced. The powder was found to withstand highcompression forces without affecting the redispersion of the oildroplets upon dissolution in deionised water and the droplet sizedistribution appeared unaffected.

EXAMPLE 13

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 10 136.11 13.61 PVP k30 (40% by weight 511.87 51.19 indemineralized water) Water 295.15 29.52 Maltodextrin (40% by 56.87 5.69weight in demineralized water) Total 1000 100

Spray Drying conditions Pilot Plane Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 35:65 Inlet/outlet temperature 210° C./96°C. Yield 80.40% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release Good somecoalescence Mean droplet size before 4.0 μm, peak at 8 μm spraying

EXAMPLE 14

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 10 155.56 15.55 PVP k30 (40% by 472.60 47.2 weight indemineralized water) Water 319.44 31.9 Maltodextrin (40% 52.5 5.25 byweight in demineralized water) Total 1000.1 100

Spray Drying conditions Pilot Plane Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 40:60 Inlet/outlet temperature 210° C./95°C. Yield 74.71% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release Good littlecoalescence Mean droplet size before 3.0 μm, peak at 8 μm spraying

EXAMPLE 15

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 10 175.00 17.5 PVP k30 (40% by 433.12 43.31 weight inwater) demineralized Water 343.75 38.38 Maltodextrin (40% 48.12 4.81 byweight in demineralized water) Total 1000 100

Spray Drying conditions Pilot Plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 45:55 Inlet/outlet temperature 210° C./95°C. Yield 68.69% Comment Spray dried well, good powder produced. ProductCharacterisation Nature of dry particle Good Oil encapsulation Appearsgood from appearance but probably encapsulation lower than expected. Oilrelease Good some coalescence Mean droplet size before 4.0 μm, peak at 8μm spraying

EXAMPLE 16

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 10 136.11 13.61 Gum acacia (40% by 568.74 56.87 weightin demineralized water) Water 295.15 29.52 Total 1000 100

Spray Drying conditions Pilot Plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 35:65 Inlet/outlet temperature 210° C./95°C. Yield 82.31% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release Good butmoderate amount of coalescence Mean droplet size before 4.2 μm, peak at7.5 μm spraying

EXAMPLE 17

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. Ingredients Weight(g) % Preparation 10 136.11 13.61 Water 295.15 29.52 Maltodextrin (40%by 568.74 56.87 weight in demineralized water) Total 1000 100

Spray Drying conditions Pilot Plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 35:65 Inlet/outlet temperature 210° C./96°C. Yield 69.25% Comment Spray dried well but lower yield than Example 16Product Characterisation Nature of dry particle Moderate Oilencapsulation Some free oil visible Oil release Large amount ofcoalescence Mean droplet size before 7.4 μm, peak at 9 μm spraying

EXAMPLE 18

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. The dispersion wassheared for 2 minutes on a Silverson disperser before spraying to ensuregood mixing. Ingredients Weight (g) % Preparation 11 116.67 11.66Modified starch 612.5 61.25 (40% by weight in demineralized water) Water270.88 27.09 Total 1000 100

Spray Drying conditions Pilot Plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 210° C./96°C. Yield 98.70% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release Good somecoalescence Mean droplet size before 7.6 μm, peak at 8 μm spraying

“Modified starch” is a chemically modified food starch with a dextroseequivalent value of 32-37%.

EXAMPLE 19

The dispersion was prepared by stirring the biliquid foam and water intothe aqueous polymers immediately before spray drying. The dispersion wassheared for 2 minutes on a Silverson disperser before spraying to ensuregood mixing. Ingredients Weight (g) % Preparation 12 116.67 11.66Modified starch 612.5 61.25 (40% by weight in demineralized water) Water270.88 27.09 Total 1000.5 100

Spray Drying conditions Pilot Plant Tests were carried out in a 1 mdiameter pilot spray drying tower with downward co current air flow.Atomisation was carried out with a two fluid nozzle. Total non volatiles35% Oil:polymer (dry basis) 30:70 Inlet/outlet temperature 210° C./95°C. Yield 94.06% Comment Spray dried well Product Characterisation Natureof dry particle Good Oil encapsulation Good Oil release Good, littlecoalescence Mean droplet size before 9.26 μm, peak at 9 μm spraying

“Modified starch” is a chemically modified food starch with a dextroseequivalent value of 32-37%.

FOOTNOTE TO THE EXAMPLES

Trade Name Supplier INCI Name Dow Corning Dow Corning Silicone 200 50cstEtocas 25 Croda PEG-25 Castor Oil Chemicals Gransil DMCM-5 GrantCyclopentasiloxane Chemicals (D5)(and)Polysilicone- 11 (and)Dimethicone. (An Organopolysiloxane mixture) Gransil GCM-5 GrantCyclopentasiloxane Chemicals (D5)(and)Polysilicone- 11 (An Organopoly-siloxane mixture) Isopar K Exxon Isoparaffin Chemical Ltd Kathon ICG 11Chesham Mixture of: 5-chloro Chemicals 2-methyl-4-isothia- Limitedzolin-3-one and 2- methyl-4-isothiazolin- 3-one KMC RutgersDiisopropylnaphthalene Kureha isomers (mixture) Solvents GmbH Mowiol4-88 Kuraray Polyvinyl alcohol, Specialties partly saponified EuropePergascript Ciba Bisindolylphthalide red I-6B Specialties compound Tween20 Fisher Polysorbate 20 Chemicals

1. A discrete powder which comprises particles in which a biliquid foamhas been entrapped within a matrix of a polymeric material.
 2. A powderas claimed in claim 1 which is a spray dried powder, a freeze driedpowder or a powder produced by fluidized bed granulation.
 3. A powder asclaimed in claim 1 which has a mean particle size in the range of from 5to 150 μm.
 4. A powder as claimed in claim 1 wherein the polymericmaterial encapsulating the biliquid foam is selected fromcarboxymethylcellulose, hydroxyethylcellulose, cetylhydroxycellulose,hydroxypropylcellulose, hydroxylprepylmethylcellulose,hydroxyethylmethylcellulose methyicelluloss, gelatine, gum arabic, gumacacia, gellan gum, shellac, carragenan, natural starch, modifiedstarch, xanthan gum, an alginate, a dextrin, polyvinyl alcohol,polyvinyl acetate, polyvinylpyrollidone or a polyamide, or mixturesthereof.
 5. A powder as claimed in claim 1 wherein the biliquid foamcomprises a substantially water immiscible internal oil phase whichcomprises a cyclomethicone, dimethicone, phenyl trimethicone,dimethiconol, dimethicone copolyol, trimethylsiloxysilicate, isopropylisostearate, lanolate, myristate or palmitate, or octyl palmitate,avocado oil, coconut oil, soybean oil or sunflower oil, acaprylic/capric triglyceride, a lanolin oil, orange oil, mineral oil ornatural oil, or oleyl alcohol or mixtures thereof.
 6. A powder asclaimed in claim 5 which comprises from 5% to 50% by weight of an oil,based upon the weight of the powder.
 7. A process for the preparation ofa discrete powder which comprises a biliquid foam entrapped within amatrix of a polymeric material, which process comprises the steps of: i)preparing a biliquid foam, ii) forming a dispersion of the biliquid foamin an aqueous solution, suspension or dispersion of a polymericmaterial, and iii) subjecting the dispersion to drying under conditionssuch that a discrete powder is formed.
 8. A process as claimed in claim7 wherein the drying is carried out by spray drying or freeze drying ofthe dispersion, or subjecting the dispersion to a fluidized bedgranulation process.
 9. A process as claimed in claim 7 wherein thebiliquid foam prepared in step (i) has a mean droplet size in the rangeof from 1 to 45 micrometres.
 10. A process as claimed in claim 7 whereinthe biliquid foam has a droplet size of below 12 micrometres.
 11. Aprocess as claimed in claim 7 wherein the polymeric material is selectedfrom carboxymethylcellulose, hydroxyethylcellulose,cetylhydroxycellulose, hydroxypropylcellulose,hydroxypropylmethylcellulose, hydroxyethylmethyl cellulose,methylcellulose, gelatine, gum arabic, gum acacia, gellan gum, shellac,carragenan, natural starch, modified starch, xanthan gum, an alginate, adextrin, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrollidone or apolyamide, or mixtures thereof.
 12. A process as claimed in claim 7wherein the biliquid foam comprises an essentially water immiscibleinternal oil phase which comprises a cyclomethicone, dimethicone, phenyltrimethicone, dimethiconol, dimethicone copolyol,trimethylsiloxysilicate, isopropyl isostearate, lanolate, myristate orpalmitate, octyl palmitate, avocado oil, coconut oil, soybean oil orsunflower oil, a caprylic/capric triglyceride, a lanolin oil, orangeoil, mineral oil or natural oil, or oleyl alcohol, or mixtures thereof.13. A process as claimed in claim 7 wherein the continuous phase of thebiliquid foam is an aqueous phase.
 14. A process as claimed in claim 7wherein the aqueous phase includes therein a C₁-C₄ alcohol or ethyleneglycol.
 15. A process as claimed in claim 7 wherein the spray dryingconditions comprise an inlet temperature in the range of from 170 to210° C. and an outlet temperature in the range of from 85 to 110° C. 16.A process as claimed in claim 7 wherein the discrete powder has a meanparticle size in the range of from 5 to 150 μm.
 17. A process as claimedin claim 7 wherein the discrete powder is subjected to granulation orformed into tablets.
 18. A fragrance composition or a deodorizingcomposition which comprises a powder as claimed in claim 1 in which afragrance or deodorizing material is entrapped within an encapsulatingpolymer that allows the release of the fragrance or deodorizing materialover time, or by rupture of the encapsulating polymer on the applicationof pressure, or by dissolution of the encapsulating polymer on contactwith a solvent therefor.
 19. A diaper, incontinence paid or femininehygiene product which incorporates therein a fragrance composition or adeodorizing composition as claimed in claim
 17. 20. A fragrancing devicewhich incorporates therein a fragrance composition as claimed in claim13.
 21. A deodorizing device which incorporates therein a deodorizingcomposition as claimed in claim
 18. 22. A tamper proof seal whichcomprises a flexible film incorporating therein or having coated thereona powder as claimed in claim 1, the encapsulating polymer used in theformation of the said powders rupturing when deformed and the oilcontained within the powder particles comprising a colourless precursorof a coloured dye which, on release, undergoes a chemical change tobecome highly coloured.
 23. A hard surface cleaning product whichcomprises a powder as claimed in claim 1, the encapsulating polymer usedin the formation of the said powders being water soluble and the oilcontained within the powder particles comprising a household cleaningoil, the powder being provided as a dry surface on an applicator.